#define _CRT_SECURE_NO_WARNINGS 1
#include<iostream>

using namespace std;

class Solution {
public:
	int Fibonacci(int n)
	{
		if (n == 0)
		{
			return 0;
		}
		else if (n > 0 && n <= 2)
		{
			return 1;
		}
		else
		{
			return Fibonacci(n - 1) + Fibonacci(n - 2);
		}
	}
};

int main()
{
	class Solution sl;
	int n;
	cin >> n;
	cout << sl.Fibonacci(n);
	return 0;
}